Polymeric hardeners for gelatin



United States Patent 214,815. Divided and this application Get. 8, 1965,

Ser. No. 516,181

2 Claims. (Cl. 260-8) This invention relates to hardeners for gelatin either when used as such or when used as the carrier for silver halide in photographic emulsions. These hardeners are polymeric in form and contain both carboxyl and unsaturated hydrocarbon aldehyde or maleimido-radicals. This application is a division of our copending application Serial No. 214,815, filed August 6, 1962, and now abandoned.

Various hardeners for gelatin have been suggested such as in the preparation of photographic products. Many photographic products contain several gelatin layers in sandwich form and it is often desirable to differentially harden these layers to a different degree determined by the task that each layer is to perform. The simple organic hardeners are prone to migrate from layer to layer, hence, differential hardening is difiicult to achieve. As a result of this migration, the various layers of the photographic products tend to harden equally.

One means of anchoring the hardening function in a compound to be used for this purpose has been to unite a radical or grouping of high molecular weight with a radical or grouping of lower molecular weight which exerts a hardening effect. In the present invention, the prevention of migration is achieved by the use of a polymeric hardener in the gelatin composition.

One object of our invention is to provide hardeners for gelatin which resist migration from the layer in which they are present to an adjacent layer. Another object of our invention is to provide polymeric hardeners for gelatin having a polymeric chain which acts as a ballast for hardening groupings attached thereto. A further object of our invention is to provide polymers in whicha large number of hardening sites may be attached to the backbone of the hardener. A still further object of our invention is to provide polymeric hardeners which are suitable in aqueuos systems such as those in which gelatin is normally used and which are compatible with gelatin both Wet and dry. A still further object of our invention is to provide polymeric hardeners for gelatin containing both carboxyl groups and unsubstituted unsaturated hydrocarbon terminal radicals, aldehyde radicals or maleimido radicals. Other objects of our invention will appear herein.

We have found that polymeric hardeners having a polymeric backbone and substituents thereon which provide (l) carboxyl groups and (2) unsubstituted unsaturated hydrocarbon terminal groups, aldehyde groups or maleimido groups are resistant to migration from one gelatin layer to another. These polymers incorporated in gelatin or in compositions containing gelatin such as silver halide emulsions will provide the layers coated out therefrom with good resistance to melting and swell. The hardening agents in accordance with our invention have a hardening effect on gelatin when used therewith in almost any proportion but a proportion of at least 1% based, on the gelatin, is ordinarily most desirable. The optimum range for the use of the hardeners in gelatin compositions is ordinarily 540% based on the weight of the gelatin.

In its broadest aspects our invention relates to the use as hardeners for gelatin of polymers of which the linear portion is a linear polymeric chain having the structure 3,338,075 Patented Mar. 7, 1967 of an addition polymer of the polyhydrocarbon type or the structure of a condensation polymer such as of a polypeptide for instance gelatine (recurring CO-NH units) of a polyanhyd roglucose, for instance cellulose or of a poly-amide, for instance nylon. The polymeric chain or backbone should have appended thereto reactive groups such as hydroxyl, amino, carboxy halide oranhydride through which the hardening groups areattached. The hardeners in accordance with our invention are polymers having substituents on the recurring units supplying carboxyl and unsubstituted unsaturated hydrocarbon terminal groups, aldhyde radicals or maleimido groups. It is desirable that these hardeners have a carboxyl content of at least 3% to insure water. solubility and compatibility with gelatin. They should also have at least 2% of unsubstituted unsaturated hydrocarbon groupings, aldehyde radicals or maleimido groups or combinations thereof in chemical combination in the polymer. Polymers having the above described characteristics are useful as non-migrating hardeners for gelatin.

Some compounds which illustrate hardeners of this type are the following: A. Copoly(ethylene N-aldehydomethyl maleamic acid) n being at least 20.

:1 being at least 20 and x and y are 1 to 5.

C. Copoly(ethylene-beta-maleimidoethyl acid maleatel n being at least 20.

D. Copoly(acrylic acid-beta-maleimidoethyl acrylate) x being at least 20. E. Copoly(vinyl alcohol-vinyl acrylate-vinyl acetate-vinyl acid succinate) where w, x, y and z are integers within the range 1-5 and n is at least 20.

F. Copoly(viny1 acryloxyethylcarbamate-vinyl acid succiuate) HNCHICH OfiCH CHQ x and y being 1-5 and n is at least 20. G. Copoly(ethylene-beta-vinylsulfonylethyl acid maleate) n being at least 20.

Samples of the various compounds listed above were added to separate portions of a high speed gelatin-silver bromoiodide photographic emulsion which had been panchromatically sensitized with a cyanine dye. The emulsion used contained 245 grams of gelatin per mole of silver halide. Each emulsion sample was coated on a cellulose acetate support at the rate of 430 mg. of silver per square foot. The coatings were compared with controls without hardener. A sample of each coating was exposed on an Eastman 1 B sensitometer, processed for 5 minutes in Kodak DK50 developer, fixed, washed and dried. The results obtained were as follows:

G./100 g. Rel. Melting Hardener of gelatin Speed 1 Fog P oint, Swell The lower speeds in the emulsions which had been hardened appears to be due to someslowing down of the development rate as hardening action in general, does decrease the permeability of an emulsion layer to developer solution.

Examples of preparing polymeric hardeners useful in compositions of the invention are as follows:

Example 1.C0p0ly(ethyZene-N-aldehydomel'hyl maleamic acid) A solution of 10 grams (0.08 mole) of ethylene-maleic anhydride copolymer in 100 ml. of acetone was tumbled for 3 days with 10.8 grams (0.08 mole) of aminoacetaldehyde. diethyl acetaL. The viscosity of the solution increased markedly. The product was precipitated in ether, washed with ether and vacuum dried giving 20 grams of product. This polymeric product was dissolved in a mixture of 200 ml. of water and 200 ml. of dimethylformamide and the solution was tumbled with 50 grams of ion exchange resin (Amberlite IR 120) for 3 days. The solution was filtered and the filtrate was added to 750 ml. of water containing 2 grams of sodium hydroxide. The solution was dialyzed overnight and was then evaporated down to 100 ml. and used for addition to gelatin compositions for hardening purposes. This product had an ethoxyl content of 20.7% and a nitrogen content of approximately 5%, based on the weight of the entire product.

Example 2.C0poly(ethylene-maleimidomethyl acid maleate) Example 3.--C0p0ly(ethylene-beta-maleimidoethyl acid maleate) 6.3 grams of ethylene-maleic anhydride interpolymer of the thus obtained product was suspended in 50 m1. of was placed in a glass reflux outfit equipped with a mechanical stirrer. Eight grams of beta-hydroxyethylmaleimide, 50 ml. of hexamethylphosphoramide, 6.5 ml. of dry pyridine, and a small amount of hydroquinone were added and the mass was heated and stirred on a steam bath for 40 minutes to form a derived polymer. The dope obtained was cooled and poured into two liters of ether in a fine stream thereby precipitating the polymer formed. The product was extracted with ether and dried in a vacuum desiccator to give 10 grams of product. Eight grams of the thus obtained product was suspended in 50 ml. of distilled water, chilled in an ice bath and mechanically stirred, and 10% aqueous sodium hydroxide was added dropwise, keeping the pH below 7 throughout. Solution was complete with the final pH of 6.4. The weight was adjusted to grams, making the solids content 10%.

Example 4.C0p0ly (acrylic acid-beta-maleimidoethyl acrylate) Poly acrylic anhydride (rather than ethylene-maleic anhydride polymer), beta-hydroxyethylmaleimide, hexamethylphosphoramide, pyridine, and hydroquinone in the amounts given in the preceding example were mixed together and treated in an identical manner. The yield of the product was 10.3 grams. Seven grams of this product was doped in 35 ml. of distilled water in the manner described in the previous example maintaining the pH below 6.4. 72 grams of dope at pH 6.3 was obtained having a content of 9.7% of copoly(acrylic acid-beta-maleimidoethyl acrylate).

Example 5.-Cop0ly(vinyl acrylate-viny[acetate-vinyl acid saccinate) 22 grams of polyvinyl alcohol containing about 12 mole percent of combined vinyl acetate were dissolved in 220 ml. of hexamethylphosphoramide by heating to 150 C. The clear smooth dope was cooled to 50 C. and a small amount of hydroquinone and then 20 ml. of acrylyl chloride were added. The reaction vessel was placed in a 50 C. bath and after one hour at this temperature ml.

of pyridine and 50 grams of succinic anhydride were added and the temperature was raised to 60 C. The mass was kept at 60 C. for 21 /2 hours. The resulting dope was diluted with an equal volume of water and poured in a fine stream into 10 liters of acetone with stirring. The precipitate obtained was extracted with acetone and was then dissolved in 250 ml. of water. 338 grams of dope having a solids content of 13.4% was obtained determined by drying a weighed sample at C. and weighing the residue. The polymer obtained contained 27.1% of combined vinyl acid succinate.

Example 6.-Coply(ethylene-beta-vinylsulfonylethyl acid maleate) Example 7 .C opoly ethylene-m ucochloryl acid maleate) 25.2 grams of ethylene maleic anhydride copolymer and 33 grams of mucochloric acid were dissolved in 250 ml. of dimethylformamide and the solution was heated for one hour on a steam bath. The mixture turned dark. It

was precipitated in ether, washed, redissolved in acetone,

and reprecipitated in ether, washed and vacuum dried. A

uct was precipitated in acetone, washed, and vacuum dried. 12 grams of beta-acrylyloxyethyl carbamyl gelatin was obtained.

Example 10.Acrylyl carbamyl gelatin A solution of 10 grams of gelatin and 200 ml. of dimethyl sulfoxide was made as in the previous example. This was treated with 4 grams of acrylyl isocyanate. The solution was allowed to stand overnight and was then precipitated in acetone, giving a white powder, 6.4 grams of acrylylcarbamyl gelatin was obtained.

Samples of the compounds prepared by Examples 7, 8, 9, and 10 were added to separate portions of a high speed silver bromoiodide emulsion which had been panchro matically sensitized with a cyanine dye. Each emulsion was coated on cellulose acetate film support at a silver coverage of 432 mg. per square foot and a gelatin coverage of 980 mg. per square foot. The coatings were compared with controls without hardener. Each coating was exposed on an Eastman 1B sensitometer, processed for minutes in Kodak DK-SO developer, fixed, washed and dried. The results obtained were as follows:

Cone. Percent Product Example g./100g Rel. Speed Gamma Fog Swell" F. Ret. F. Ml.

of gel (Vert) Control 100 1.34 0.09 652 79 85 Example VII 1 87 1.30 0.08 678 79 89 5 72 1.32 0 08 568 79 89 68 1.21 0.07 503 79 83 Example VIII 1 80 1.11 0.12 581 82 91 5 80 1.02 0.14 339 None 212 10 67 .94 0.14 216 None 212 Control 100 1.58 0. 13 863 80 87 Example IX 1 105 1 .60 0.13 632 94 125 5 87 1.49 0.11 640 None 212 1O 83 1.33 0.10 348 None 212 Example X 1 105 1.52 0.13 776 83 5 105 1.30 0.20 596 83 89 10 80 1.34 0.24 385 86 102 Vertical swell was determined after the strip had been immersed at 68 F. in distilled water.

yield of 23 grams of copoly(ethylene-mucochloryl acid maleate) was obtained.

Example 8.-C0p0lymer of N-acrylyl-O-mucochloryl carbamate-maleic anhydride A solution of 50 grams of mucochloric acid and 100 ml. of acetone was added dropwise with ice cooling to a solution of grams of acrylyl isocyanate in 100 ml. of ether under nitrogen. The mass was allowed to stand overnight whereupon a crystalline solid precipitated. Upon cooling in a freezer and filtering, 16 grams of crude product was obtained. This product was recrystallized from acetone giving 12 grams of white needles of N-acrylyl-O-mucochloryl carbamate (M.P. 161162 0.).

8 grams of the N-acrylyl-O-mucochloryl carbamate so prepared and 3.8 grams of maleic anhydride were dissolved in 200 ml. of benzene and the solution was heated with 0.2 gram of benzoyl peroxide on a steam pot. The mixture started to polymerize almost immediately. The mass was heated for 4 hours then the mass was cooled, filtered, washed with benzene, and vacuum dried. A copolymer of acrylyl mucochloryl carbamate and 25 mole percent of maleic anhydride was thereby obtained (1;-0.1 1) which product had good gelatin hardening properties.

Example 9.Beza-acrylyloxyelhyl carbamyl gelatin A mixture of 15 grams of gelatin and 300 ml. of dry dimethyl sulfoxide was tumbled for four days. Most of the gelatin went into solution. After filtering, there was added to the filtrate 1.5 grams of isoyanatoethyl acrylate and the resulting solution was allowed to stand overnight. It was then heated for one hour in a 60 bath. The prod- The hardeners in accordance with our invention are of special value for use in photographic products in which a plurality of gelatin layers are applied one over the other because of their resistance to migration from layer to layer. The photographic products may employ various types of supports such as cellulose ester film, film of other types or paper supports, the type of support used being optional with the individual operator. In addition to the hardening of photographic emulsion layers, also contemplated is the hardening of gelatin layers employed as overcoatings, subcoats, antistatic layers, antihalation layers or the like which layers may contain pigments, dyes or any of the other addenda which have been incorporated in gelatin layers in the making of photographic products.

We claim:

1. A composition of matter comprising gelatin containing as a hardener therein an effective hardening amount of copoly(ethylene-mucochloryl acid maleate).

2. A composition of matter comprising gelatin contain ing as a hardener therein an effective hardening amount of copolymer of N-acrylyl-O-mucochloryl carba-matemaleic anhydride.

References Cited by the Examiner FOREIGN PATENTS 6/1938 Great Britain. 2/ 1961 Great Britain. 

1. A COMPOSITION OF MATTER COMPRISING GELATIN CONTAINING AS A HARDENER THEREIN AN EFFECTIVE HARDENING AMOUNT OF COPOLY(ETHYLENE-MUCOCHLORYL ACID MALEATE).
 2. A COMPOSITION OF MATTER COMPRISING GELATIN CONTAINING AS A HARDENER THEREIN AN EFFECTIVE HARDENING AMOUNT OF COPOLYMER OF N-ACRYLYL-O-MUCOCHLORYL CARBAMATEMALEIC ANHYDRIDE. 